Baby cribs are fairly well known to comprise a mattress that is fixed at a relatively low level within a protective enclosure, normally having a pair of side panels that may be manually raised or lowered. The distance between the mattress height and the top of the side panels is set high enough to limit a baby's ability to climb out of the crib.
While offering good protection to most infants, this does require a person to awkwardly bend over the side panels to reach the baby, or to first drop the side panel to move the baby into or out of the crib. Even with the panel lowered, the mattress level is typically at a height which puts strain on the lower back.
In U.S. Pat. No. 3,022,154, a crank mechanism is used to adjust the height of a mattress in a crib, so that this may be raised or lowered. However, this is a fairly time consuming process and often it would be quicker and more convenient to avoid use of the crank. Another drawback is that should the mattress be left at a higher position, for convenience, it makes it more likely that a baby could climb over the enclosure and fall out of the crib.
In U.S. Pat. No. 2,590,337, an electrically powered raising and lowering system uses a pair of limit switches to set an upper position and a lower position, so that by activating a switch mounted on a side of the crib, the mattress is raised until the upper limit switch is contacted, which turns the power off to the unit. Activating the switch again reverses the direction and causes the mattress to be lowered until the lower limit switch is reached. By design, this is a two position system and has the drawback that there is no control between these two positions. Stopping at an intermediate position is not possible.
Another drawback with prior systems is that there is no coordination with the side panel. While the side panel may be manually moved in some cases, the side panel movement is not integrated with a mattress elevation system. Consequently, even with the mattress raised to a certain level, there is some difficulty in placing the baby in the crib, or taking the baby out of the crib.